<!DOCTYPE html>
<meta charset="UTF-8">
<title>test for which value of interpolate-size is used</title>
<link rel="help" href="https://drafts.csswg.org/css-values-5/#interpolate-size">

<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<body>
<script>
for (let allow of [false, true]) {
  for (let from_keyword of [false, true]) {
    let used_interpolate_size = allow ? "allow-keywords" : "numeric-only";
    let other_interpolate_size = allow ? "numeric-only" : "allow-keywords";
    let from_width = from_keyword ? "min-content" : "100px";
    let to_width = from_keyword ? "100px" : "min-content";

    test(t => {
      let e = document.createElement("div");
      e.id = "t1";
      document.body.append(e);
      t.add_cleanup(() => e.remove());

      let s = document.createElement("style");
      s.append(`
        #t1 {
          interpolate-size: ${other_interpolate_size};
          width: ${from_width};
          transition: width 10s 1000s step-end;
        }
        #t1[title] {
          width: ${to_width};
          interpolate-size: ${used_interpolate_size};
        }
      `);

      document.head.append(s);
      t.add_cleanup(() => s.remove());

      let cs = getComputedStyle(e);
      assert_equals(cs.width, from_keyword ? "0px" : "100px", "width before change");
      e.title="a title";
      assert_equals(cs.width, (allow ^ from_keyword) ? "100px" : "0px", "width after change");
    }, `Use the after-change value of interpolate-size: ${used_interpolate_size} when starting CSS transition from ${from_width} to ${to_width}`);

    test(t => {
      let e = document.createElement("div");
      e.id = "t2";
      document.body.append(e);
      t.add_cleanup(() => e.remove());

      let s = document.createElement("style");
      s.append(`
        @keyframes kf2 {
          0% {
            width: ${from_width};
            interpolate-size: ${other_interpolate_size};
          }

          100% {
            width: ${to_width};
            interpolate-size: ${other_interpolate_size};
          }
        }
        #t2 {
          interpolate-size: ${used_interpolate_size};
          animation: kf2 10s -1s linear;
        }
      `);

      document.head.append(s);
      t.add_cleanup(() => s.remove());

      let cs = getComputedStyle(e);
      let expected = from_keyword ? 0 : 100;
      if (allow) {
        expected = expected * 0.9 + (100 - expected) * 0.1;
      }
      assert_equals(cs.width, `${expected}px`, "width with animation");

    }, `Use the non-animation value of interpolate-size: ${used_interpolate_size} when starting CSS animation from ${from_width} to ${to_width}`);
  }
}
</script>
